1. Field of the Invention
The present invention relates to a new method for synthesizing zeolite ZSM-5 and to use of the ZSM-5 synthesized hereby as catalyst for certain chemical conversion reactions. More particularly, it relates to making and using ZSM-5 which, in its as synthesized form, is comprised of highly twinned, rectangular prismatic crystals exhibiting extremely uniform size of between about 5 .times. 10 microns and about 10 .times. 20 microns.
2. Summary of the Prior Art
Zeolite ZSM-5 is a relatively new zeolite which in its conventionally synthesized aluminosilicate form has the following composition expressed in terms of mole ratios of oxides in the anhydrous state: EQU (0.9 .+-. 0.2)M.sub.2/n O : Al.sub.2 O.sub.3 : xSiO.sub.2
wherein M is selected from the group consisting of a mixture of tetraalkylammonium cation, the alkyl groups of which contain 2-5 carbon atoms, and alkali metal cations, especially sodium, and x is at least 5, said cations having the valence n. ZSM-5 has a distinctive X-ray diffraction pattern which further identifies it from other known zeolites. The original alkali metal cations of ZSM-5 can be exchanged by ion exchange with other ions to form species of the zeolite which have exceptional catalytic properties. Zeolite ZSM-5 and its conventional preparation are the subject of U.S. Pat. No. 3,702,886, the disclosure of which is incorporated herein by reference.